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1st Solar Orbiter Summer School"Towards a Deeper Understanding of the

Sun and the Heliosphere with Solar Orbiter"

L'Aquila, September 22-25, 2014

RPW: Measuring Solar Radio and Plasma Waves

Milan MaksimovicLESIA & CNRS, Paris Observatory – France

milan.maksimovic@obspm.fr

Outline Plasma waves versus Radio waves Plasma waves : what do we observed and

understand ? Radio waves : what do we observed and

understand ? « Extra » science : Dust measurements On the difficulty of measuring the DC/LF

electric component of plasma waves RPW : a brief description

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𝝀𝝀𝑫𝑫 =𝜺𝜺𝟎𝟎𝒌𝒌𝑩𝑩𝑻𝑻𝒏𝒏𝒆𝒆𝟐𝟐

𝟏𝟏/𝟐𝟐

λD

𝜱𝜱 𝒓𝒓 =𝑸𝑸

𝟒𝟒𝟒𝟒𝜺𝜺𝟎𝟎𝒓𝒓𝒆𝒆−𝒓𝒓 𝟐𝟐/𝝀𝝀𝑫𝑫

+Q

Plasma waves versus radio wavesDebye Screening

𝝀𝝀𝑫𝑫 ≈ 𝟔𝟔𝟔𝟔 𝑻𝑻/𝒏𝒏 in S.I. units• λD ≈ 10 m @ 1 AU• λD ≈ 5 m @ 0.3 AU• λD ≈ 1 m @ 10 Rs

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What if the charge +Q moves at a speed 𝒗𝒗 ?

• 𝒗𝒗 must be compared to both 𝑽𝑽𝒕𝒕𝒕𝒕𝒕𝒕 ≈ 𝒌𝒌𝑩𝑩𝑻𝑻/𝒎𝒎𝒕𝒕 and 𝑽𝑽𝒕𝒕𝒕𝒕𝒆𝒆 ≈ 𝒌𝒌𝑩𝑩𝑻𝑻/𝒎𝒎𝒆𝒆

• If 𝒗𝒗 < 𝑽𝑽𝒕𝒕𝒕𝒕𝒕𝒕 < 𝑽𝑽𝒕𝒕𝒕𝒕𝒆𝒆 then both electrons and ions have time « to participate » to the screening of +Q

• If 𝑽𝑽𝒕𝒕𝒕𝒕𝒕𝒕 < 𝒗𝒗 < 𝑽𝑽𝒕𝒕𝒕𝒕𝒆𝒆 then only the electrons have time « to participate » to the screening of +Q

• If 𝑽𝑽𝒕𝒕𝒕𝒕𝒕𝒕 < 𝑽𝑽𝒕𝒕𝒕𝒕𝒆𝒆 < 𝒗𝒗 then there is no screening of +Q

𝝉𝝉 ≈𝜺𝜺𝟎𝟎𝒎𝒎𝒆𝒆

𝒏𝒏𝒆𝒆𝟐𝟐𝟏𝟏/𝟐𝟐

≡𝟏𝟏𝝎𝝎𝒑𝒑

Timescale for screening ?• Let’s put suddenly a charge +Q in a plasma at equilibrium• The electrons, which move faster, will need a time 𝝉𝝉 to travel a

distance 𝝀𝝀𝑫𝑫 at the most probable speed 𝑽𝑽𝒕𝒕𝒕𝒕𝒆𝒆

• 𝑭𝑭𝒑𝒑 = 𝟔𝟔 𝒏𝒏 in S.I. units• 𝑭𝑭𝒑𝒑 ≈ 𝟐𝟐𝟎𝟎 𝐤𝐤𝐤𝐤𝐤𝐤 @ 1 AU• 𝑭𝑭𝒑𝒑 ≈ 𝟔𝟔𝟎𝟎 𝐤𝐤𝐤𝐤𝐤𝐤 @ 0.3 AU• 𝑭𝑭𝒑𝒑 ≈ 𝟎𝟎.𝟓𝟓 𝐌𝐌𝐤𝐤𝐤𝐤 @ 10 Rs

𝝎𝝎𝒑𝒑 = 𝟐𝟐𝟒𝟒𝑭𝑭𝒑𝒑 is the angularplasma frequency

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Electron Density and Temperature fromQuasi-Thermal Noise Spectroscopy

2 Maxwellians:

cold : nc, Tchot : nh, Th

Antenna geometry and size matter e- passing closer than λD → F < FP → thermal plateau e- passing further than λD → Langmuir waves @ F < FP

Power ∝ 𝐹𝐹𝑃𝑃/𝐹𝐹 3

In practice 𝑳𝑳/𝝀𝝀𝑫𝑫 ≥ 𝟏𝟏 is needed : satisfied at perihelion and in dense SW

RPW should measure ne & Te with accuracies respectively of a few % and 10 % 5

Waves with 𝑭𝑭 < 𝑭𝑭𝑷𝑷𝒕𝒕 < 𝑭𝑭𝑷𝑷𝒆𝒆 are « seen » by bothions and electrons. They are screened and do not propagate

Waves with 𝑭𝑭𝑷𝑷𝒕𝒕 < 𝑭𝑭 < 𝑭𝑭𝑷𝑷𝒆𝒆 are not « seen » by ions but are still screened by the electrons

Waves with 𝑭𝑭𝑷𝑷𝒕𝒕 < 𝑭𝑭𝑷𝑷𝒆𝒆 < 𝑭𝑭 are not seen by the plasma and propagate freely

Plasma Waves

Radio Waves

By the way …

𝑭𝑭𝑷𝑷 ≈ 𝟓𝟓𝐌𝐌𝐤𝐤𝐤𝐤

𝑭𝑭𝑷𝑷 < 𝟓𝟓 𝐌𝐌𝐤𝐤𝐤𝐤

𝑭𝑭𝑷𝑷 < 𝟓𝟓 𝐌𝐌𝐤𝐤𝐤𝐤6

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In practice it is more complicated … There is a Magnetic Field Magnetic in the Solar Wind

which imposes new time and length scales (gyro-radii and –frequencies)

Full zoo of waves (see a good Plasma Physics textbooks)

In-situ Plasma waves :what do we observed and

understand ?

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𝑟𝑟−4/3

Stverak, PhD thesis

Waves are believed to both heat & accelerate the Solar Wind

RPW range for magneticfluctuations

Full range for electric

Turbulent heating/dissipation in the Solar WindKinetic Alvèn Waves ? Whistler Waves ?

Coherent structures ? Other ?

δB2

δE2

Turbulent energy cascade from large to small scales

kρ

powe

r

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Evidences for Kinetic Alven Waves turbulence ?

δE 2

δB 2

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On Cluster electric measurementsnot easy because of S/C charging

Spin tone in the raw E datadue to : illumination variations on the

probes wake effects

Spin tone needsto be filtered

Caveats

Evidences for a Cascade well above the proton scales up to the electron typical

scales (gyroscale and above ?)

Exponential decrease or power law ? Observational limitations : noise floor both for dE2 and dB2

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Alexandrova et al., ApJ 2012

Even with the same search coilsensitivity as on Cluster, RPW willmake important improvements

A fonction of the ion thermal pressure

Similar to the behaviour in the « far » dissipation range in usual fluid turbulence 𝑬𝑬(𝒌𝒌) ∝ 𝒌𝒌𝟑𝟑𝒆𝒆−𝒄𝒄𝒌𝒌𝒍𝒍𝒅𝒅 ?

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SW2

SW1

Polarized fluctuations => spectra with bumps (10% of data) Non-polarized fluctuations => permanent (or background) turbulence (90% of data, Alexandrova et al. 2012, 2013) Permanent turbulence + sporadic polarized fluctuations => “intermediate” spectral shape (breaks, small bumps, …)

Coherent waves are also observedfor e.g Whistler waves (Lacombe et al., 2014)

Maksimovic et al., 2005

Can these Whistler waves explain the radial evolution of electron VDFs ?

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Wavelet analysis of CLUSTER SCM waveforms

And even solitary structures …For e.g. Alexandrova et al. 2006, JGR

Presence of time-localized events in the vicinity of Alfvén Ion Cyclotron wave

Full characterization with the 4 CLUSTER S/C of localized AlvènVortices : role for the dissipation ?

Alexandrovaet al.

2006, JGR

Radio waves :what do we observed and

understand ?

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Solar Radio Bursts

300 KhZ

300 KHz

100 KhZ

100 KHz

Solar Type III radio emissions

1 MHz

1 MhZ

time

F

∝

∝

(au) 1

)(cm(kHz)2

3-

RN

NF

e

ep

R1 ∝→ pF

ElectrostaticLangmuir waves→ radio emission

Combined RHESSI / NRH / Phoenix/Dam/WIND-WAVES observations

Metric to hectometric emissions first !

Type III & Type IIsolar radio bursts

Type II : Shockacceleratedelectrons

Type III : flareacceleratedelectrons

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Adapted from [Ergun et al., 1998]

Adapted from [Lin et al. 1981]

Swaves

In-situ Type III and II measurements will be available on SO

RPW improvements for in-situ waves measurements

RPW will measure bothLangmuir waves and densityfluctuations (from S/C pot.

fluctuations, biased antennas)DC E field and cross-shock

potential

RPW will measure simultaneously 2-axis E + 1 axis

B up to 500 kHz → mode conversion

Ergun et al, 2008

Onboard statistics of LW power

Distribution of LW power more Pearson like than Normal ? (Vidojevic et al., 2010)

Prob.

Log10(PSD(E2))

WINDPearson

type Inormal

Interplanetary Dust

Temporal domain

Spectral domain 25

Discovery of a large flux of nanoduston Stereo Meyer-Vernet et al., 2012

Picked-up by the -VXB field

On the difficulty of measuring the DC/LF electric component of

plasma waves

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Basics for measuring DC/LF E Field

Protons :Ip∝Np Vp

Negligible at0th order

PhotoelectronsIph∝Nph Vph corrected for Φ

SW electronsIe∝Ne Vthe corrected for Φ

Φ

Φ determined by Ip + Ie + Iph = 0,actually Ie = - Iph (depending mostly on Ne)

Secondary electrons(from impact of external energetic electrons

UV

Φ1 Φ2

L12 |E| = | Φ2 – Φ1 | / L12

Salem et al., 2001

Φ varies with Ne !!We want to

measure ~mV/m !!

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courtesy C. Cully

Ie + Iph +Ibias= 0We need to bias the antennas

δΦΕ = ?

Φ2

Φ1 = Φ * 1 + δΦE

If Φ *1 = Φ 2 then Φ2 − Φ1 = δΦE

For that we need :- Equal illumination for 1 & 2- Symmetry with respect to the S/C- Biasing the probes

1

3 2

E

TypicallyIf Φ *1 = Φ 2 ~ 0 to 10 VoltsE ~ few to few 100s of mV/m

δΦΕ = ?

Φ2

Φ1 = Φ * 1 + δΦE

Leff can only be determined by simulation

1

3 2

EδΦΕ = E . Leff Leff

If Φ *1 = Φ 2 then Φ2 − Φ1 = δΦE

For that we need :- Equal illumination for 1 & 2- Symmetry with respect to the S/C- Biasing the probes

TypicallyIf Φ *1 = Φ 2 ~ 0 to 10 VoltsE ~ few to few 100s of mV/m

δΦΕ = ?

Φ2

Φ1 = Φ * 1 + δΦE

1

3 2

EδΦΕ = E . Leff

Leff

The problem is that there is a S/C in addition to the RPW antennas !!

Need to simulate the effect of the S/C

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RPW : a (very) brief description

Antennas

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5 kbps

→ shock & in-situ Type III detection

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Bibliography (1/2)

• Alexandrova O.., A. Mangeney, M. Maksimovic, N. Cornilleau-Wehrlin, J.-M. Bosqued, M. André & E.A. Lucek, Alfvénvortex filaments observed in the magnetosheath downstream of quasi-perpendicular bow-shock,Journal of Geophysicalresearch, 111, A12208, doi:10.1029/2006JA011934, 2006

• Alexandrova O., J. Saur, C. Lacombe, A. Mangeney, J. Mitchell, S. J. Schwartz, and P. Robert, Universality of Solar-Wind Turbulent Spectrum from MHD to Electron Scales, Phys. Rev. Lett. 103, 165003 – Published 14 October 2009

• Alexandrova O., C. Lacombe, A. Mangeney, R. Grappin, M. Maksimovic, Solar Wind Turbulent Spectrum at Plasma KineticScales, Astrophysical Journal, 760, DOI:10.1088/0004-637X/760/2/121, 2012.

• Bale S.D., P. J. Kellogg, F. S. Mozer, T. S. Horbury, and H. Reme, Measurement of the Electric Fluctuation Spectrum of Magnetohydrodynamic Turbulence, Phys. Rev. Lett. 94, 215002 – Published 2 June 2005

• Ergun R.E. et al., WIND SPACECRAFT OBSERVATIONS OF SOLAR IMPULSIVE ELECTRON EVENTS ASSOCIATED WITH SOLAR TYPE III RADIO BURSTS, THE ASTROPHYSICAL JOURNAL, 503:435È445, 1998

• Lacombe C., O. Alexandrova, L. Matteini, O. Santolik, N. Cornilleau-Wehrlin, A. Mangeney Y. de Conchy and M. Maksimovic, Whistler mode waves and the electron heat flux in the solar wind: Cluster observations, Journal of Geophysical Research, in press 2014

• Lin R.P., et al., Energetic electrons and plasma waves associated with a Solar Type III radio burst, The Astrophysicaljournal, 251:364-373, 1981

• Maksimovic M., S. Hoang, N. Meyer-Vernet, M. Moncuquet, J.-L. Bougeret, P. Canu and J. L. Phillips, The Solar Wind Electron Parameters from Quasi-Thermal Noise Spectroscopy and Comparison with other Measurements on Ulysses, Journal of Geophysical Research, 100, 19,881-19,891, 1995.

• Maksimovic M., K. Issautier, S.D. Bale, N. Vilmer, M. Moncuquet, N. Meyer-Vernet and J.-L. Bougeret, Solar Wind Electron Temperature and Density Measurements for the Solar Orbiter using the Thermal Noise spectroscopy, Solar encounter, Proceedings of the First Solar Orbiter Workshop, 14 - 18 May 2001, Puerto de la Cruz, Tenerife, Spain, ESA SP-493, ISBN 92-9092-803-4, p. 285, 2001.

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Bibliography (2/2)

• Maksimovic M., I. Zouganelis, J.-Y. Chaufray, K. Issautier, E.E. Scime, J. Littleton, E. Marsch, D.J. McComas, C. Salem, R.P. Lin, and H. Elliott , Radial Evolution of the Electron Distribution Functions in the Fast Solar Wind between 0.3 and 1.5 AU, J. Geophys. Res., 110, A09104, doi:10.1029/2005JA011119, 2005.

• Meyer-Vernet & Perche, Tool kit for antennae and thermal noise near the plasma frequency, Journal of GeophysicalResearch: Space Physics, Volume 94, Issue A3, pages 2405–2415, DOI: 10.1029/JA094iA03p02405, 1989

• Meyer-Vernet N., S. Hoang, K. Issautier, M. Maksimovic, R. Manning, M. Moncuquet and R.G. Stone, Measuring plasma parameters with thermal noise spectroscopy, AGU Monograph on Measurements Techniques in Space Plasmas, Geophysical Monograph 103, 1998.

• Meyer-Vernet N., M. Maksimovic, A. Czechowski, I. Mann, I. Zouganelis, K. Goetz, M.L. Kaiser, O.C. St. Cyr, J.-L. Bougeret, S.D. Bale, Dust detection by the wave instrument on STEREO: nanoparticles picked-up by the solar wind?, Solar Physics, 256: 463-474, DOI 10.1007/s11207-009-9349-2, 2009.

• Sahraoui F., M. L. Goldstein, P. Robert, and Yu. V. Khotyaintsev, Evidence of a Cascade and Dissipation of Solar-Wind Turbulence at the Electron Gyroscale, Phys. Rev. Lett. 102, 231102 – Published 10 June 2009

• Salem C., et al., Determination of accurate solar wind electron parameters using particle detectors and radio wavereceivers, Journal of Geophysical research, 106, 21,701, 2001

• Stverak S., M. Maksimovic, P. Travnıcek, E. Marsch, A.N. Fazakerley and E.E. Scime, Radial Evolution of Non-thermal Electrons in the Low-latitude Solar Wind: Helios, Cluster and Ulysses observations, J. Geophys. Res., 114, A05104, doi:10.1029/2008JA013883, 2009.

• Vidojevic S., A. Zaslavsky, M. Maksimovic, O. Atanackovic, S. Hoang and Q. N. Nguyen, LangmuirWaves and Type III Bursts Observed by the Wind Spacecraft, in: (M. Maksimovic, K. Issautier, N. Meyer-Vernet, M. Moncuquet, F. Pantellini, Eds.) Proceedings of the 12th Solar Wind Conference, Saint Malo, France, 22 - 26 June 2009,, AIP CP. 1216, 284, 2010.

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